Rock-drill bit



' I Oct.12,1926. 1,602,498

E. W. MCCANNA I ROCK DRILL. BIT

iled Dec. 2s, 1 923 Patented Get. 12, 1926.

PATENT OFFICE- EDWARD W. MGCANNA, OF BUTTE, MONTANA.

ROCK-DRILL BIT.

Application filed December 26, 1923. Serial No. 682,776.

This invention relates to rock drill bits.

It is an object to provide a drill bit which combines with the advantage of simplicity and cheapness of manufacture the advantage I that it cuts faster and maintains its gauge longer than other forms of bits in use.

For a full understanding of the invention, its characteristic features and the points of novelty, reference is made to the accompanying drawings in which- Fig. 1 is a perspective view of a drill bit embodying the invention;

Fig. 2 is an end view thereof;

Fig. 3 is an elevation; and

Fig. & a section of the line 4-4, Fig. 2.

The drill bit, which is principally intended for drilling in mines and quarries where blasting is required, is not intended to disintegrate the rock by a cutting action or by a chipping action, as is usually the case, but operates on the principle of crumbling the underlying material. It comprises a plurality of (preferably four) reaming segments separated from each other by relatively wide and deep radial grooves 11.

The bit is of the type having a central bore. The width of the grooves is substantially or approximately equal to the diameter of the axial bore 12 for the reason to be more particular pointed out.

The segments have moderately beveled surfaces 13 and 1 1 defining radial cutting or crushing edges 15 lying in substantially the same plane at right angle to the axis of the bit. The lateral edges, which together with the edges 15 define the surfaces 13 and 14, converge inwardly to the inner end of the cutting edges 15, preferably to points lying in a circle concentric with the axis of the bit.

The grooves 11 open into grooves 16 running lengthwise through the peripheral portion of the expanded part of the bit.

The structural and functional significance of the bit is as follows:

The bit is easily formed by die and dollie, no forming or swaging blocks being required. The cutting and reaming edges do not require resharpening as often as other forms of bits now in use and the resharpening operation is relatively simple and cheap.

In using hollow drill steel with this bit,

the steel does not clog with cuttings for the reason that the bore 12in the bit does not extend to the'bottom of the drill hole or to the rock, but terminates a considerable distance above it and the cuttings can be effectively washed out through the grooves 11 and 16. This constitutes a most important advantage in drilling operations.

The drill works well with or without rotation, and several different lengths of steel may be used without change in the gauge of the bit, as is necessary with other forms of bits. v

I am. fully aware that many forms of bits of the pure impact type are in use or have been proposed and I am familiar with the practical operation thereof. However, the relatively deep grooves which are in- 7 strumental in avoiding clogging, together with the rugged cutting and reaming segments which effect the crumbling of the rock, mark a distinct advance in the drilling art. 7

I claim 1. A drill bit having a plurality of cutting and reaming segments separated by relatively deep radial grooves and a central bore terminating at the bottom of the grooves, each segmentpresenting moderately beveled surfaces defining a central radial cutting edge and lateral edges converging to the inner end of the radial edge.

2. A drill bit having a plurality of cutting and reaming segments separated by relatively deep radial grooves of substantially uniform depth and a central bore terminating at the intersection of thegrooves, the segments having moderately beveled sur- 00 faces defining a central radial cutting edge and converging edges meeting at the inner end of the cutting edge.

3. A drill bit having four cutting and reaming segments separated by relatively deep radial grooves of substantially uniform depth and a central bore terminating at the intersection of the grooves, the segments having moderately beveled surfaces defining a central radial cutting edge and converging edges meeting at the inner end of the cutting edge, the meeting points lying in a circleconcentric with the bit.

i. A drill bit ha'ving a plurality of cutting and reaming segments separated by relatively deep radial grooves of substantial- 1y uniform depth and a central bore terminating at the bottom of the grooves, the segments having surfaces sloping from a central radial cutting edge toward the grooves and terminating a substantial distance above the bottom thereof defining the bit.

In testimony whereof, I aflix my signatnre.

EDWARD W. MCCANNA. 

